1. Field of the Invention
The present invention relates to bowl mill transmissions, and particularly to a bowl mill transmission with a vertically arranged bevel-gear stage for power input and a multi-stage transmission arrangement for power input to a thrust plate of a bowl-mill crusher.
2. Description of the Related Art
The invention is based on bowl mills which are driven by vertical bevel-gear transmissions.
The prior art includes drives of this kind (e.g., Renk Tacke company publication Kegelrad-Planetengetriebe KPAV fxc3xcr vertikale Wxc3xa4lzmxc3xcu hlen [Epicyclic bevel-gear transmissions for vertical roller mills]) in which the bevel-ear stage outputs power into the sun gear of an epicyclic transmission with a fixed annulus. In such transmissions, power output to the grinding bowl is via the planet carrier, which accommodates a plurality of planet gears for power transmission.
The grinding process in such mills requires high power transmission to the grinding stock at low speeds of rotation and high torque. The high transmission ratios required for this purpose are limited by the maximum possible diameter of the transmission stage and the diameter of the horizontal bevel gear. The diameter of the epicyclic stage is limited by the transmission housing which passes the grinding forces into the mill foundation by direct force transmission.
Developments of such drives embody two epicyclic stages. Here, the bevel-gear transmission drives a first sun pinion of a first epicyclic transmission stage. A second epicyclic transmission stage is driven by means of a rotationally fixed connection of the planet carrier, which rotates in the fixed annulus, to a further sun gear, which is arranged axially above the first sun gear. This second epicyclic stage is arranged axially above and concentrically to the first. By way of a further planet carrier, which revolves in a further fixed annulus by means of its planet gears, which are provided for power splitting, it outputs power into the grinding bowl.
The prior-art transmissions consume high input power to move the large revolving masses. A considerable outlay for bearings is furthermore required and assembly of the many individual parts is difficult. Furthermore, the bearings installed in revolving planet carriers can be monitored only with extreme difficulty.
It is accordingly an object of the present invention to provide a transmission which has a high overall transmission ratio with a large output torque, is of compact construction, and is simple to assemble.
According to an aspect of the invention, this object is achieved by a bowl mill transmission having a bevel-gear stage that inputs power via a pinion of a first transmission stage into gear arranged on a gear shaft. A further gear axially displaced along the gear shaft outputs power into an annulus of a further transmission stage which is rotationally fixed to the output thrust plate.
In each of its various overall sizes, the transmission design according to the invention covers a broader power range than the prior art and extends the power spectrum upwards.
By virtue of the compact stage unit according to the invention, the transmission can to a very large extent be preassembled, making assembly easier.
By virtue of the advantageous nonrevolving arrangement, fixed relative to the housing, of the gears, their bearing arrangements in transmissions according to the invention are simple to lubricate and monitor. Moreover, the toothings can be provided with splash lubrication.
By virtue of the advantageous simple tooth engagement of the gears, there is no alternating bending stress on the tooth roots, and the teeth thus have higher tooth-root bearing capacities or can be made with smaller dimensions.
While maintaining grinding performance, more compact plants with a significantly lower weight can be achieved with the transmission arrangement according to the invention.
By virtue of the advantageous drive configuration, the transmission according to the invention can be constructed on a modular basis.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.